Chaperone Proteins

Chaperone proteins play a role in the unfolding and folding of proteins, their assembly and disassembly, and help to translocate organelles. They are part of a family called heat shock proteins that play important roles in the functioning of proteins. The name ‘heat shock proteins’ was given after they were found in bacteria, making more proteins when they were put under a stressful environment, (e.g. high/low temperatures or pH) hence the name ‘heat shock proteins.’ 

Some examples of heat shock proteins are Hsp70 and Hsp60. Hsp70 focuses on the folding of proteins, and is involved in the different processes such as refolding or misfolding of proteins, and also catalyze processes for folding new proteins. Hsp70 finds a part of the unfolded polypeptide chain, called the “extended region” and when Hsp70 binds to these proteins, it stops the aggregation of these proteins. Aggregation of proteins is when proteins that are mutated or misfolded start to come together and create clumps that steer into diseases and conditions such as Alzheimer's or Parkinson's disease. Hsp60 does not directly partake in stopping aggregation, but instead focuses on isolating unfolded proteins. By isolating these proteins, it stops the polypeptide chain from aggregating. 

Hsp60 has 14 different protein components. The proteins that it is composed of form two rings which each have 7 proteins, and then these rings are stacked up. Any unfolded proteins that are contained inside the rings do not face complications when aggregating with any other proteins. 

There has also been a rise in therapeutic uses of Hsp inhibitors. Currently, Hsp 90 inhibitors can be used to hinder any signaling pathways that play a role in the growth of tumor cells. Chemical chaperones also have an application in metabolic diseases. For example, endoplasmic reticulum stress is caused by a collection of any unfolded/misfolded proteins. Chemical chaperones can be used as a treatment for this, as they play a role in helping protein folding occur correctly. When chemical chaperones help in the process, they have a positive effect on ER-stress,  which then plays a role in halting disorders such as type 2 diabetes. 

The use of different chaperone proteins helps to create a web of workers in the cell that allows proteins to remain in homeostasis, and to make sure these proteins are folding correctly in environments that are deemed unsuitable for spontaneous folding. These chaperone proteins are extremely important in the cytoplasm as they not only are a huge factor in stopping the aggregation of proteins, but also play a role in translocation and degradation. Without these chaperone proteins, multiple diseases have a higher risk of occurring, demonstrating the importance of the roles chaperone proteins play in our cells.

References:

 “What Are Chaperone Proteins?” News-Medical, 22 Aug. 2023, www.news-medical.net/life-sciences/What-are-Chaperone-Proteins.aspx.

“How Chaperones Fold Proteins.” PubMed, 1 Mar. 1998, pubmed.ncbi.nlm.nih.gov/9563819. 

Merlini, G., et al. “Protein Aggregation.” Clinical Chemistry and Laboratory Medicine (CCLM), vol. 39, no. 11, Jan. 2001, https://doi.org/10.1515/cclm.2001.172.

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